In manufacturing pneumatic tires, the green tire is placed in a curing press wherein an inflatable curing bladder, supplied with steam, followed by nitrogen, which expands and presses the tire against a mold. The product is heated and then cures. The bladder is then deflated and then mold is opened to remove the cured product or tire. The process is repeated to manufacture multiple tires.
During curing, it is important that the desired curing pressure and temperature be maintained to cure the tire. If the bladder develops an undetected leak, this curing pressure and temperature can be reduced causing a defectively cured tire. If the leaking bladder remains undetected after multiple defective tires are cured, a significant number of scrap tires can be generated with one defective bladder since tires are visually inspected only after the curing process.
Attempts have been made to detect leaks in a tire curing process. For example, U.S. Pat. No. 5,417,900 discloses pulling a vacuum on the bladder and curing media piping. If a certain level of vacuum is not achieved within a time limit, the operator is notified that a leak exists in the system. However, bladders may develop very small pin holes that may not be detected by this system. Furthermore, the bladder may fold over on itself blocking the holes, which would not be detected by this system.
Thus, there is a need provide an improved leak detection system for detecting leaks in a curing bladder and thereby reduce the manufacture of scrap tires.